Field of Invention
An embodiment relates generally to a liquefied gas treatment system.
Description of Related Art
With recent technological advances, liquefied gas, such as liquefied natural gas or liquefied petroleum gas, which replaces gasoline or diesel, has come into widespread use.
Liquefied natural gas is natural gas that is converted into liquid form by cooling methane obtained by refining natural gas extracted from the gas field. Liquefied gas is a colorless, transparent liquid, and it is a fine fuel that produces little pollution and has a high calorific value. On the other hand, liquefied petroleum gas is a fuel made by compressing gas, which is mainly composed of propane (C3H8) and butane (C4H10), extracted along with petroleum from oilfields, into liquid form at room temperature. Like liquefied natural gas, liquefied petroleum gas is colorless and odorless and has been widely used as household, commercial, industrial and automobile fuel.
The above-described liquefied gas is stored in a liquefied gas storage tank installed on the ground or on a ship which is a means of transportation sailing on the ocean. Liquefied natural gas takes up about 1/600 the volume of natural gas in its gaseous state. Propane and butane of liquefied petroleum gas take up about 1/260 and 1/230 the volume of petroleum gas in its gaseous state, respectively. Therefore, liquefied gas has high storage efficiency.
Such liquefied gas is supplied to and used by various sources of demand. In recent years, an LNG fuel supply method by which an LNG carrier drives an engine using LNG as a fuel has been developed. This method of using LNG as a fuel in an engine is also applicable to other ships.
However, the temperature and pressure of liquefied gas required by a source of demand, such as an engine, may be different from a state of liquefied gas stored in a liquefied gas storage tank. Therefore, recently, the technique of controlling the temperature and pressure of liquefied gas, which is stored in liquid state, and supplying the liquefied gas to a source of demand has been researched and developed.